Due to the invention of light and fiber, a remarkable success has been achieved in a fiber technology. Under the promotion of optical communication technology, great progress has been made in the research and development of all kinds of devices, such as optical fiber, devices, components, instruments and mechanical devices. As everyone knows, the optical wave is an electromagnetic wave; when the electromagnetic wave is emitted in a medium such as a fiber, the incident electromagnetic wave will interact with molecules or atoms forming the material, so as to generate scattering spectra, which commonly comprises Rayleigh scattering and Brillouin scattering. By using the scattered light information, people develop a lot of sensing fiber monitoring instruments. Since Mendes and other people firstly embedded a fiber sensor in a concrete structure to monitor the structure safety in 1989, scholars of all countries further promoted the application of the technology in construction and hydraulic engineering. At present, the fiber sensing technology has obtained some achievements on composite material solidification monitoring, nondestructive examination of structure, damage monitoring and identification and evaluation aspect.
In hydraulic engineering and civil engineering, the interior of the material may have fracture of different degrees under the effects of external temperature, water loading, weight, etc. The fracture is invisible internal damage under many conditions, and if the fracture cannot be detected and found in time, it is possible to develop into a potential safety hazard in the engineering. This defect or damage may have a continuously accumulated and irreversible process with the time, which may cause whole or partial sudden invalidation of the structure body, so as to lead to a serious engineering problem. The material may release elastic energy in damage, the elastic energy is transmitted in the form of elastic wave in the material, and the elastic wave is called an acoustic emission wave.
But regarding currently developed monitoring devices, the actual application of the fiber sensing technology lags far behind the requirement on the technology currently due of the variety of current performance parameters and the requirement of high standard, wherein the fusion sensing fiber technology and the acoustic emission technology are one of the fields lacking research. Since the sensing fiber technology and the acoustic emission technology have good monitoring and detecting performance, the fusion thereof will generate great technical improvement, so as to break through the piezoelectric ceramic acoustic emission detection method with a large system, many cables and bad anti-electronic logging interference ability and the current fiber bragg grating acoustic emission testing system of point mode monitoring.